Scientists Propose New Explanation For Flu Virus Antigenic Drift

Influenza viruses evade infection-fighting antibodies by constantly changing the shape of their major surface protein. This shape-shifting, called antigenic drift, is why influenza vaccines -- which are designed to elicit antibodies matched to each year's circulating virus strains -- must be reformulated annually. Now, researchers from the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, have proposed a new explanation for the evolutionary forces that drive antigenic drift. The findings in mice, using a strain of seasonal influenza virus first isolated in 1934, also suggest that antigenic drift might be slowed by increasing the number of children vaccinated against influenza.

Scott Hensley, Ph.D., Jonathan W. Yewdell, M.D., Ph.D., and Jack R. Bennink, Ph.D., led the research team, whose findings appear in the current issue of Science.

"This research elegantly combines modern genetic techniques with decades-old approaches to give us new insights into the mechanisms of antigenic drift and how influenza viruses elude the immune system," says NIAID Director Anthony S. Fauci, M.D.